Rough Estimation, if they keep throwing broken characters like chaze we'll soon reach the 100% power creep state where nothing matters anymore beside 10 powerhouse characters. Balance your game now...
I think zeta abilities really adds diversity, but till zeta is obtained it feels pretty unbalanced with many characters that are simply underpowered in arena, and raids, and only a handful of characters being widely used. And, it takes a long time till zetas are unlocked.